1. Field of the Invention
The present invention relates to a cylindrical lithium rechargeable battery, and more particularly, to a cylindrical lithium rechargeable battery that may prevent deformation and breakage of a cap assembly.
2. Discussion of the Background
As generally known in the art, a cylindrical lithium rechargeable battery may include an electrode assembly wound in the form of a cylinder, a cylindrical can for receiving the electrode assembly therein, an electrolyte contained in the cylindrical can to enable lithium ions to move, and a cap assembly coupled with the cylindrical can to prevent the electrolyte from leaking and to prevent the electrode assembly from separating from the cylindrical can.
This type of cylindrical lithium rechargeable battery may have a capacity of about 2.000 to 2,400 mA, and thus may be used for applications that require a large power capacity, such as for a notebook PC, a digital camera, or a camcorder. A plurality of cylindrical lithium ion rechargeable batteries may be coupled with each other in a row or in series and assembled with a protection circuit in the form of a hard pack to be used as a power source for electronic appliances.
A cylindrical lithium rechargeable battery may be fabricated as described below. First, an electrode assembly may be prepared by sequentially stacking a negative electrode plate coated with an active material, a separator, and a positive electrode plate coated with an active material, and then winding the negative electrode plate, the separator, and the positive electrode plate in the form of a cylinder. End portions of the negative electrode plate, the separator, and the positive electrode plate may be coupled to a rod-type winding shaft. The cylindrical electrode assembly may be accommodated in a cylindrical case and an electrolyte may be injected into the cylindrical case. Then, the cap assembly may be welded to an upper portion of the cylindrical case to complete the cylindrical lithium rechargeable battery.
A core member in the form of a rod may be inserted into the center portion of the electrode assembly to prevent the electrode assembly from deforming during charging and discharging of the cylindrical lithium ion rechargeable battery.
However, a core member provided in a conventional cylindrical lithium rechargeable battery may easily move if an external impact is applied to the cylindrical lithium rechargeable battery, such as when the battery falls to the ground. If the core member moves within the electrode assembly, the cap assembly provided on the upper portion of the electrode assembly may be damaged. If the core member collides with a safety vent, the safety vent may be inversely deformed or broken, which may degrade the safety of the cylindrical lithium ion rechargeable battery.